Transitioning to Exchange 2010

Transition is the scenario in which you upgrade an existing Exchange organization to Microsoft Exchange Server 2007. To perform the transition, you must move data from the existing Exchange servers to new Exchange 2010 servers. For example, when upgrading from an Exchange 2007 organization to an Exchange 2010 organization, you perform a transition.

Migration is the scenario in which you upgrade to Exchange 2010 by migrating data from a non-Exchange messaging system to Exchange 2010 or from an existing Exchange organization to a completely new Exchange organization, without retaining any of the Exchange configuration data in the first organization. For example, when merging with another company, you can perform a migration. In this scenario, you move mailboxes and data to the other company's Exchange organization, without retaining any of the configuration data from your existing Exchange organization. Another example is when upgrading from Lotus Notes to Exchange 2010, you perform a migration. In this scenario, you must move mailboxes and data to the new Exchange 2010 organization, without retaining any of the data from the Lotus Notes organization.

Important:

When transitioning to Exchange 2010, you cannot perform an in-place server upgrade on an existing Exchange server. Instead, you must install a new Exchange 2010 server into the existing organization, and then move data to the new Exchange 2010 server.

The transition process happens in several phases. In each phase, you introduce individual Exchange 2010 server roles and transport features. At the conclusion of each phase, the organization will have coexistence of Exchange 2010 with Exchange 2003 or Exchange 2000 and will be running in a supported coexistence mode. The end-to-end process is designed to maintain messaging functionality and stability throughout the transition process. The migration process includes installing a completely new Exchange 2010 organization, and then migrating mailboxes from the old messaging system to the new Exchange 2010 messaging system, using various tools for migration.

You can migrate from Lotus Notes to Exchange 2010 by installing Exchange 2010 in a new organization and migrating existing mailboxes. You can only transition to Exchange 2010 from the following existing messaging systems:

Exchange 2007 messaging system

Combined Exchange 2003 and Exchange 2007 messaging system

This means that if you are upgrading from an Exchange 2003 or Exchange 2007 organization, you can choose to either transition the organization, or migrate to a new organization. In most cases, you will want to retain the Exchange data from the existing organization, and so you should choose to transition to Exchange 2010.

If you are upgrading from any messaging system besides Exchange 2003 or Exchange 2000, your only option is to migrate to Exchange 2007.